Double-tower flash evaporation energy-saving device in gasification system

Abstract

The utility model relates to a double-tower flash evaporation energy-saving device in a gasification system. Comprising a gasification furnace connected with an outlet of a coal mill and an oxygen pipeline connected with the gasification furnace, a gas phase outlet of the gasification furnace is connected with a cyclone separator, a gas phase outlet of the cyclone separator is connected with a water scrubber, and a gas phase outlet of the water scrubber is connected with a subsequent conversion section. A liquid phase outlet of the gasification furnace, a liquid phase outlet of the cyclone separator and a liquid phase outlet of the water scrubber are respectively connected with a primary evaporation hot water tower, a liquid phase outlet of the primary evaporation hot water tower is connected with an inlet of a secondary evaporation hot water tower, and a liquid phase outlet of the secondary evaporation hot water tower is connected with an ash water gas-liquid separation circulating unit through a vacuum flash evaporator; the method has the advantages that the process design is reasonable, the heat energy utilization rate is increased, the use amount of circulating cooling water is reduced, the operation cost of a gasification system is reduced, the lower-layer slurry is recycled, so that the particle size distribution of the coal slurry is adjusted, the concentration of the coal slurry is increased, and the gasification efficiency is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of gasification systems, in particular to a double-tower flash evaporation energy-saving device in a gasification system. Background Art

[0002] In the existing technology, the gasification system generates high-temperature and high-pressure black water through the gasification furnace. The high-temperature and high-pressure black water needs to undergo three-stage flash evaporation and then solid-liquid separation. The gray water after solid-liquid separation can be used as washing water for the water washing tower, and the ash residue after solid-liquid separation is sold externally; the aforementioned three-stage flash evaporation process requires a large amount of circulating water to exchange heat for the high-temperature and high-pressure black water, and at the same time, the gray water after solid-liquid separation requires steam to heat it to meet the requirements of the water washing tower; that is, the operation of the existing gasification system requires the consumption of a large amount of circulating water and steam, resulting in a waste of water resources and heat sources, further increasing the operating costs of the enterprise. Utility Model Content

[0003] In view of the deficiencies in the prior art, the utility model provides a double-tower flash evaporation energy-saving device in a gasification system to solve the defects in the prior art.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is:

[0005] A dual-tower flash evaporation energy-saving device in a gasification system comprises a gasifier connected to a coal mill outlet, and an oxygen pipeline connected to the gasifier, the gas phase outlet of the gasifier is connected to a cyclone separator, the gas phase outlet of the cyclone separator is connected to a water scrubber, the gas phase outlet of the water scrubber is connected to a subsequent conversion section, the liquid phase outlet of the gasifier, the liquid phase outlet of the cyclone separator, and the liquid phase outlet of the water scrubber are respectively connected to a first-level evaporative hot water tower, the liquid phase outlet of the first-level evaporative hot water tower is connected to an inlet of a second-level evaporative hot water tower, the liquid phase outlet of the second-level evaporative hot water tower is connected to a gray water gas-liquid separation circulation unit through a vacuum flash evaporator; the upper hot water section inlet of the second-level evaporative hot water tower is connected to a raw water tank, the upper hot water section outlet of the second-level evaporative hot water tower is connected to the upper hot water section inlet of the first-level evaporative hot water tower, and the upper hot water section outlet of the first evaporative hot water tower is connected to the circulating water inlet of the water scrubber.

[0006] The beneficial effects of the present invention are as follows: by arranging a first-level evaporation hot water tower, a second-level evaporation hot water tower and a vacuum flash evaporator, and utilizing the characteristics of the black water after flash evaporation to utilize its thermal energy, the consumption of water resources can be reduced under the premise of fully utilizing the thermal energy; specifically, the present invention utilizes the flash steam in the second-level evaporation hot water tower to preheat the circulating water, and further, the flash steam in the first-level evaporation hot water tower is used to perform deep heat exchange on the preheated circulating water to increase its temperature entering the water washing tower, and finally achieves the characteristic of improving the water vapor ratio in the synthesis gas leaving the gasification boundary zone.

[0007] Preferably, the grey water gas-liquid separation circulation unit comprises at least a clarifier, the raw water tank is connected to the upper hot water section inlet of the secondary evaporative hot water tower via a raw water pump and a first tee, and the supernatant outlet of the clarifier is connected to the third end of the first tee.

[0008] Preferably, the supernatant outlet of the clarifier is connected to the gray water tank, and the outlet of the gray water tank is connected to the third end of the first tee through a gray water pump.

[0009] Preferably, the bottom slurry outlet of the clarifier is connected to the filter press through a slurry pump and a second tee, and the third end of the second tee is connected to the coal mill inlet.

[0010] Preferably, the gas phase outlet at the top of the vacuum flash evaporator is connected to the heat exchange channel of the desalted water preheater, the heat exchange channel outlet of the desalted water preheater is connected to the inlet of the clarification tank; the desalted water channel inlet of the desalted water preheater is connected to the desalted water pipeline, and the desalted water channel outlet of the desalted water preheater is connected to the deaerator.

[0011] Preferably, the top gas phase outlets of the first-stage evaporative hot water tower and the second-stage evaporative hot water tower are respectively connected to a flare device.

[0012] Preferably, a first water supply pump is provided between the upper hot water section outlet of the secondary evaporative hot water tower and the upper hot water section inlet of the primary evaporative hot water tower, and a second water supply pump is provided between the upper hot water section outlet of the primary evaporative hot water tower and the circulating water inlet of the water washing tower.

[0013] According to the above scheme, a double-tower flash evaporation energy-saving device in a gasification system is manufactured. By utilizing the characteristics of high-temperature and high-pressure black water, a first-level evaporation hot water tower and a second-level evaporation hot water tower are set to perform flash evaporation on it. The second-level evaporation hot water tower preheats the circulating washing water, and the first-level evaporation hot water tower heats the preheated circulating washing water to make the temperature entering the water washing tower 200-210°C, which is higher than the temperature of the washing water entering the traditional water washing tower (the traditional temperature is about 150°C). The above method can not only effectively utilize thermal energy and save a large amount of cooling water, but also achieve the characteristic of improving the water vapor ratio in the synthesis gas leaving the gasification boundary zone. In addition, the utility model utilizes the relatively clean flash gas in the vacuum flash evaporator to heat the desalted water to meet its needs as a deaerator; the utility model utilizes the lower layer slurry that passes through the clarifier to flow back to the coal mill, and utilizes the high solid content, small particle size and coal content in the lower layer slurry to adjust the particle size distribution of the coal slurry, thereby increasing the coal slurry concentration and thus improving the gasification efficiency. It has the advantages of reasonable process design, improved thermal energy utilization, reduced use of circulating cooling water, reduced gasification system operating costs, and reuse of the lower layer slurry to adjust the particle size distribution of the coal slurry to increase the coal slurry concentration and thus improve the gasification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the present utility model.

[0015] In the picture:

[0016] 1. Coal mill; 2. Gasifier; 3. Oxygen pipeline; 4. Cyclone separator; 5. Water scrubber; 6. Subsequent conversion section; 7. First-stage evaporation hot water tower; 8. Second-stage evaporation hot water tower; 9. Vacuum flash evaporator; 10. Raw water tank; 11. Circulating water inlet; 12. Clarifying tank; 13. Raw water pump; 14. First tee; 15. Ash water tank; 16. Ash water pump; 17. Slurry pump; 18. Second tee; 19. Filter press; 20. Desalted water preheater; 21. Desalted water pipeline; 22. Deaerator; 23. Flare device; 24. First feed water pump; 25. Second feed water pump. DETAILED DESCRIPTION

[0017] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0018] See Figure 1 : The utility model is a double-tower flash evaporation energy-saving device in a gasification system, comprising a gasifier 2 connected to the outlet of a coal mill 1, and an oxygen pipeline 3 connected to the gasifier 2, the gas phase outlet of the gasifier 2 is connected to a cyclone separator 4, the gas phase outlet of the cyclone separator 4 is connected to a water scrubber 5, the gas phase outlet of the water scrubber 5 is connected to a subsequent conversion section 6, the liquid phase outlet of the gasifier 2, the liquid phase outlet of the cyclone separator 4 and the liquid phase outlet of the water scrubber 5 are respectively connected to a first-level evaporation hot water tower 7, the liquid phase outlet of the first-level evaporation hot water tower 7 is connected to the inlet of a second-level evaporation hot water tower 8, the liquid phase outlet of the second-level evaporation hot water tower 8 is connected to a ash-water gas-liquid separation circulation unit through a vacuum flash evaporator 9; the upper hot water section inlet of the second-level evaporation hot water tower 8 is connected to a raw water tank 10, the upper hot water section outlet of the second-level evaporation hot water tower 8 is connected to the upper hot water section inlet of the first-level evaporation hot water tower 7, and the upper hot water section outlet of the first evaporation hot water tower 7 is connected to the circulating water inlet 11 of the water scrubber 5. The utility model realizes effective utilization of the heat energy in the high-temperature and high-pressure black water by arranging a first-level evaporation hot water tower 7 and a second-level evaporation hot water tower 8, which saves the original flash evaporator and the corresponding cooler, and saves the use of circulating cooling water; thereby achieving the characteristics of full utilization of the heat of the flash evaporation system and zero consumption of circulating water in the gasification system.

[0019] Furthermore, the graywater gas-liquid separation and circulation unit includes at least a clarifier 12. The raw water tank 10 is connected to the upper hot water section inlet of the secondary evaporative hot water tower 8 via a raw water pump 13 and a first tee 14. The supernatant outlet of the clarifier 12 is connected to the third end of the first tee 14. This arrangement enables the supernatant from the clarifier 12 to be used as wash water for the water scrubber 5. This approach effectively utilizes water resources in the gasification system and utilizes the thermal energy of the black water in the gasification system using the water resources in the gasification system, thereby recycling the water resources and thermal energy of the gasification system itself and achieving energy conservation and consumption reduction. In actual use, the present invention preferentially uses the supernatant from the clarifier 12. When the supernatant is insufficient to meet the operating requirements of the water scrubber 5, it can be supplemented with raw water from the raw water tank 10.

[0020] Furthermore, the supernatant liquid outlet of the clarifier 12 is connected to a gray water tank 15, and the outlet of the gray water tank 15 is connected to the third end of the first tee 14 via a gray water pump 16. The present invention can buffer and temporarily store the supernatant liquid from the clarifier 12 through the gray water tank 15 to ensure long-term stable operation of the gasification system. At the same time, the gray water pump 16 pressurizes the supernatant liquid for delivery to the hot water section of the secondary evaporative hot water tower 8.

[0021] Furthermore, the bottom slurry outlet of the clarifier 12 is connected to the filter press 19 via the slurry pump 17 and the second tee 18, and the third end of the second tee 18 is connected to the inlet of the coal mill 1. The bottom slurry of the clarifier 12 described in the present invention is the lower layer slurry, which has the characteristics of high solid content, low particle size and coal content. The present invention applies it to the coal mill 1 based on the above characteristics, especially for coals with high water content and high organic matter content, it is difficult to increase the coal slurry concentration during the grinding and slurrying process. The inability to increase the coal slurry concentration leads to a significant increase in the coal consumption and oxygen consumption of gasification. The present invention adjusts the particle size distribution of the coal slurry by mixing the above high solid content coal slime partly back to the coal mill to achieve the characteristics of increasing the coal slurry concentration and then increasing the gasification efficiency, thereby improving the economic benefits of the enterprise.

[0022] Furthermore, the gas phase outlet at the top of the vacuum flash evaporator 9 is connected to the heat exchange channel of the desalted water preheater 20, the heat exchange channel outlet of the desalted water preheater 20 is connected to the inlet of the clarifier 12; the desalted water channel inlet of the desalted water preheater 20 is connected to the desalted water pipeline 21, and the desalted water channel outlet of the desalted water preheater 20 is connected to the deaerator 22. Analysis shows that the flash gas produced by the vacuum flash evaporator 9 is relatively clean and has little impact on erosion and corrosion of equipment. The utility model utilizes the aforementioned characteristics of flash gas to apply it to the heating of desalted water, thereby achieving the desalted water supply demand of the deaerator 22 while recovering heat energy and without using circulating water.

[0023] Furthermore, the top gas phase outlets of the primary evaporative hot water tower 7 and the secondary evaporative hot water tower 8 are respectively connected to a flare device 23. In the present invention, the provision of the flare device 23 allows the non-condensable gas produced by the primary evaporative hot water tower 7 and the secondary evaporative hot water tower 8 to be combusted simultaneously, thereby reducing equipment purchase costs and improving equipment utilization while meeting environmental protection requirements.

[0024] Furthermore, a first water supply pump 24 is provided between the upper hot water section outlet of the secondary evaporation hot water tower 8 and the upper hot water section inlet of the primary evaporation hot water tower 7, and a second water supply pump 25 is provided between the upper hot water section outlet of the primary evaporation hot water tower 7 and the circulating water inlet 11 of the water washing tower 5.

[0025] The utility model also provides a method for a double-tower flash evaporation energy-saving device in a gasification system, the method comprising the following steps:

[0026] Step 1: Oxygen from the oxygen pipe 3 and the water-coal slurry from the coal mill 1 are fed into the gasifier 2 together, where they react under high temperature and high pressure. The gas generated by the reaction is quenched in the quenching chamber of the gasifier 2. The quenched gas enters the cyclone separator 4 to remove some fine ash and liquid. The gas passing through the cyclone separator 4 enters the water scrubber 5 for scrubbing. The scrubbed gas enters the subsequent conversion section 6 for subsequent reactions.

[0027] Step 2: The liquid phase in the gasifier 2, the liquid phase in the cyclone separator 4, and the liquid phase in the water scrubber 5 is black water, which enters the first-stage evaporation hot water tower 7 together. The pressure in the first-stage evaporation hot water tower 7 is 1.5 MPa(G). After flash evaporation, the black water rises to the hot water section through the central tube of the first-stage evaporation hot water tower 7 and undergoes mass transfer and heat exchange with the circulating water in the hot water section. The non-condensable gas after mass transfer and heat exchange enters the flare device 23 through the gas phase outlet at the top of the first-stage evaporation hot water tower 7 and is burned. The liquid phase in the gasifier 2, the liquid phase in the cyclone separator 4, and the liquid phase in the water scrubber 5 enter the first-stage evaporation hot water tower 7 at a temperature of 240-245°C and a pressure of 6.48 MPa(G).

[0028] Step 3: After flash evaporation, the liquid phase in the primary evaporation hot water tower 7 enters the secondary evaporation hot water tower 8. The pressure in the secondary evaporation hot water tower 8 is 0.2 MPa (G). The black water entering the secondary evaporation hot water tower 8 rises to the hot water section through the central tube of the secondary evaporation hot water tower 8 after flash evaporation, and performs mass transfer and heat exchange with the circulating water in the hot water section. The non-condensable gas after mass transfer and heat exchange enters the flare device 23 through the gas phase outlet at the top of the secondary evaporation hot water tower 8 for combustion;

[0029] Step 4: The black water flashed through the secondary evaporation hot water tower 8 enters the vacuum flash evaporator 9 for further flash evaporation. The pressure in the vacuum flash evaporator 9 is 25 kPa (A). The gas phase flashed out of the vacuum flash evaporator 9 enters the heat exchange channel of the desalted water preheater 20 to preheat the desalted water and then condense. The condensed condensate and the black water from the vacuum flash evaporator 9 enter the clarification tank 12 together.

[0030] The desalted water in the desalted water pipe 21 enters the desalted water channel of the desalted water preheater 20 for heat exchange and is then sent to the deaerator 22 for further deoxygenation before being used in the boiler or waste boiler.

[0031] Step 5: The black water in the clarifier 12 settles naturally, and the supernatant overflows into the gray water tank 15. The gray water in the gray water tank 15 is sent to the upper hot water section of the secondary evaporative hot water tower 8 through the gray water pump 16 as circulating water, and is heat exchanged to 115-125°C through the flash steam in the secondary evaporative hot water tower 8;

[0032] Step 6: The circulating water after heat exchange in the upper hot water section of the secondary evaporative hot water tower 8 enters the upper hot water section of the primary evaporative hot water tower 8 through the first water supply pump 24, and is heat exchanged to 200-210° C. by the flash steam in the primary evaporative hot water tower 8. The circulating water heated in the upper hot water section of the primary evaporative hot water tower 8 enters the water washing tower 5 through the second water supply pump 25 and the circulating water inlet 11 of the water washing tower 5 for use as washing water.

[0033] Step 7: After the black water naturally settles in step 5, the lower middle part of the clarification tank 12 is the lower layer slurry. The lower layer slurry is sent to the coal mill 1 through the slurry pump 17 to be mixed with the raw coal to reduce the particle size of the coal slurry. When the amount of circulating water in step 5 is small, turn on the raw water pump 13, so that the raw water in the raw water tank 10 is mixed with the first three-way valve 14 and the gray water from the gray water tank 15 and used together as circulating water. In the present utility model, gray water is preferably used as circulating water. According to the needs of actual working conditions, when the amount of gray water is small and cannot meet the washing requirements in the water washing tower, it can be supplemented with the raw water in the raw water tank 10 to maintain the normal operation of the gasification system. When there is too much slurry in step 7, the slurry pump 17 transports the lower layer slurry to the filter press 19 through the second three-way valve 18 for solid-liquid separation. The lower layer slurry in the present invention has the characteristics of high solid content, small particle size and coal content. By returning it to the coal mill, the particle size distribution of the coal slurry can be adjusted to increase the coal slurry concentration, thereby improving the gasification efficiency, so as to achieve the characteristics of improving the emergency benefits of the enterprise; the lower layer slurry described in the present invention gives priority to the use of the coal mill. When there is still excess lower layer slurry after meeting the use of the coal mill, it can enter the filter press 19 for solid-liquid separation, and the gasified ash can be sold outside.

[0034] The utility model realizes the effective utilization of high-temperature and high-pressure black water thermal energy through a two-stage evaporation hot water tower, eliminates the original low-pressure flash evaporator gas-phase circulating water cooler and vacuum flash evaporator gas-phase circulating water cooler and other related settings, concentrates the solid materials in the black water through the step-by-step flash evaporation of high-temperature and high-pressure black water, and uses the heat generated by the flash evaporation internally, changing the previous circulating water condensation, not only greatly reducing the circulating water consumption of the gasification device, but also improving the temperature of the washing water in the gasification system water washing tower, and ultimately improving the water-vapor ratio of the synthesis gas out of the gasification boundary zone, greatly increasing the amount of by-product steam in the downstream conversion section, and in addition, by partially returning the high-solid content coal slime to the pulverizer and adjusting the particle size distribution of the coal slurry, the coal slurry concentration is increased, thereby improving the gasification efficiency. In summary, it can bring huge benefits to the enterprise.

[0035] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A double-tower flash evaporation energy-saving device in a gasification system, comprising a gasifier (2) connected to the outlet of a coal mill (1), and an oxygen pipeline (3) connected to the gasifier (2), the gas phase outlet of the gasifier (2) being connected to a cyclone separator (4), the gas phase outlet of the cyclone separator (4) being connected to a water scrubber (5), and the gas phase outlet of the water scrubber (5) being connected to a subsequent conversion section (6), characterized in that: The liquid phase outlet of the gasifier (2), the liquid phase outlet of the cyclone separator (4), and the liquid phase outlet of the water washing tower (5) are respectively connected to the first-level evaporation hot water tower (7), the liquid phase outlet of the first-level evaporation hot water tower (7) is connected to the inlet of the second-level evaporation hot water tower (8), and the liquid phase outlet of the second-level evaporation hot water tower (8) is connected to the gray water gas-liquid separation circulation unit through the vacuum flash evaporator (9); The upper hot water section inlet of the secondary evaporation hot water tower (8) is connected to the raw water tank (10), the upper hot water section outlet of the secondary evaporation hot water tower (8) is connected to the upper hot water section inlet of the primary evaporation hot water tower (7), and the upper hot water section outlet of the primary evaporation hot water tower (7) is connected to the circulating water inlet (11) of the water washing tower (5).

2. The double-tower flash evaporation energy-saving device in a gasification system according to claim 1, characterized in that: The grey water gas-liquid separation circulation unit comprises at least a clarifier tank (12); a raw water tank (10) is connected to the upper hot water section inlet of the secondary evaporative hot water tower (8) via a raw water pump (13) and a first tee (14); and a supernatant outlet of the clarifier tank (12) is connected to the third end of the first tee (14).

3. The double-tower flash evaporation energy-saving device in a gasification system according to claim 2, characterized in that: The supernatant outlet of the clarifier (12) is connected to the gray water tank (15), and the outlet of the gray water tank (15) is connected to the third end of the first three-way (14) through the gray water pump (16).

4. The double-tower flash evaporation energy-saving device in a gasification system according to claim 2, characterized in that: The bottom slurry outlet of the clarifier (12) is connected to the filter press (19) through a slurry pump (17) and a second tee (18), and the third end of the second tee (18) is connected to the inlet of the coal mill (1).

5. The double-tower flash evaporation energy-saving device in a gasification system according to claim 2, characterized in that: The gas phase outlet at the top of the vacuum flash evaporator (9) is connected to the heat exchange channel of the desalted water preheater (20), and the heat exchange channel outlet of the desalted water preheater (20) is connected to the inlet of the clarifier (12); The desalted water channel inlet of the desalted water preheater (20) is connected to the desalted water pipeline (21), and the desalted water channel outlet of the desalted water preheater (20) is connected to the deaerator (22).

6. The double-tower flash evaporation energy-saving device in a gasification system according to claim 1, characterized in that: The top gas phase outlets of the first-level evaporation hot water tower (7) and the second-level evaporation hot water tower (8) are respectively connected to the flare device (23).

7. The double-tower flash evaporation energy-saving device in a gasification system according to claim 1, characterized in that: A first water supply pump (24) is provided between the upper hot water section outlet of the secondary evaporation hot water tower (8) and the upper hot water section inlet of the primary evaporation hot water tower (7), and a second water supply pump (25) is provided between the upper hot water section outlet of the primary evaporation hot water tower (7) and the circulating water inlet (11) of the water washing tower (5).

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